1. Field of the Invention
The suture-wire fixation device is a new type of orthopaedic implant for fracture fixation. It is specially devised for avulsion fractures such as patella, olecranon, and malleolus. It is composed of a suture-wire and an impactor. The front part is a metal pin and the rear part is one or multiple segments of flexible wire. After reduction of the fracture, the pin is drilled into the bone across the fracture line with the tip coming out from the other end of bone. The impactor is seated onto the end of the pin with the wire within the trough of the impactor. The pin is hammered into the bone totally. With two pins passed through the fractured bone in parallel, one of the wires is bent and looped behind two protruding tips of the pins and is tightened to the other wire by twisting of the wires. The prominent pin tips are then cut. By doing so, the fracture is tightened and will not be pulled apart by muscle forces. Compared to the ordinary way of tension band wiring of fractures, this implant causes little irritation to the soft tissue and skin, and little migration is possible. Migration may impinge onto surrounding tissues and prevent the patient from early rehabilitation and recovery. Migration is also the cause of loss of fixation which may dictate another surgery. With this device, the operation time is shortened, because there is no need for bending of the wire ends which is sometimes time consuming. In conclusion, the method of fracture fixation with the suture-wire device is a good, safe and time efficient procedure which facilitates early recovery after surgery.
2. Description of the Prior Art
For a fractured bone, generally, the method of treatment includes internal fixation with implants such as a nail, plate, screw, pin and wire to hold the bone together while it heals. For the treatment of avulsion fractures such as patella, olecranon and malleolus, the most popular method nowadays is the tension band wiring technique recommended by ASIF (Association for Study of Internal Fixation). The technique uses two Kirschner wires which pass in parallel across the fracture line, and a segment of metal wire is looped around both ends of the Kirschner wires and tightened. The wire works as a tension band which holds the fracture fragments together and compresses the fragments during physiological loading of the bone. To explain the tension band wiring technique, illustrations of the procedure for fixation of a patellar fracture is shown as below (see FIGS. 1 a-1f):
Step A: With powered drill 1, two parallel drill holes are made over the fracture end 21 of the proximal fragment 2. Once the first hole is drilled, the drill is replaced with a smaller Kirschner wire, the wire then serves as a guide for the second drill hole. PA1 Step B: Replace the Kirschner wires with 2 mm drill bits 11 inserted in proximodistal direction. Reduce the fracture fragments 2 and 2' with a pointed end reduction forceps 5. PA1 Step C: If reduction is perfect, drill with the 2 mm drill bits the holes in the distal fragment 2'. PA1 Step D: Replace drill bits by Kirschner wires 3 and 3', bent 180 degrees at proximal end into hooks 31 and 31'. PA1 Step E: Secure the wire 4 over both ends of Kirschner wires and tighten with a wire tightener. Hammer the Kirschner wires over the wire 4 with bent ends 31 and 31' into the bone. PA1 Step F: Cut the distal ends of both Kirschner wires 32 and 32', and the fixation is completed. PA1 A suture-wire device for fracture fixation includes a metal pin and wire, the anterior part is a rigid metal pin, at the end of which is a hole, the posterior part is a segment of flexible wire embedded in the hole on the pin and fixed into one piece by mechanical means such as pressing, or the like. PA1 An impactor, a metal rod with a tapered tip, has a trough which is slightly wider than the diameter of the flexible wire along the center of the rod from the tapered tip to the end. By holding the end of the pin, the pin is drilled into the bone, the anterior part of the wire is snapped into the trough of the tapered end of the impactor. The pin is hammered into the bone. By looping around the tips of two parallel pins or through a hole over the distal fragment of the fractured bone, the wires are tightened and secure fixation is achieved. Since the end of the pin is buried in the bone by impaction, no irritation of the soft tissue and skin is possible. Because the pin and wire are in one piece, no migration of the pin is possible because of the tightened wire. Since no intra-operative bending of the pin is necessary, time may be saved. From a technical point of view, the new design has apparent merits compared to the ordinary way of fixation in avulsion fracture such as patella, olecranon, malleolus, etc.
It is generally accepted that the tension bend wiring technique is effective in the fixation of a patella fracture, but some shortcomings do exist. First, the Kirschner wire is a smooth pin and may migrate during postoperative rehabilitation. The bent ends 31 and 31' are parallel to the smooth pin and frequently do not stop the migration. The sites of the fracture for application of tension bend wiring are usually superficial. Migrated Kirschner wires irritate the surrounding soft tissue and skin, produce pain and prevent the patient from early rehabilitation which is so important for an intra-articular fracture. Sometimes the wire may penetrate the skin and causes a pin tract infection. To bend the end of a Kirschner wire during operation takes time and some effort, and a perfect bend of 180 degree is not always possible. The imperfectly bent end may rotate and the wire may slip over the tip which results in loss of fixation and reduction. If the fracture fragment is small, the bending maneuver may break the bone into small pieces.